1. Field of the Invention
This invention relates to an electrical connector and, in particular, to an electrical connector having a locking mechanism for locking a connected state.
2. Description of Related Art
As an example of an electrical connector of the type, a USB connector is known. In the USB connector also, high-speed signal transmission is required. In order to increase a transmission speed in the USB connector, it is necessary to improve EMI characteristics as disclosed in JP-A-2007-103249 (Patent Document 1). Herein, referring to FIGS. 1 and 2, the technique disclosed in Patent Document 1 will briefly be described.
Referring to FIG. 1 (a connector disclosed as a conventional example in Patent Document 1), a cable connector 1 has a shell 2 provided with a friction lock hole 3. On the other hand, a board connector 4 as a mating object has a shell 5 provided with spring members 6 and 7. When the cable connector 1 is connected to the board connector 4, a part of the spring member 6 is fitted to the friction lock hole 3 to thereby lock a connected state. However, the spring member 6 is not brought into contact with the shell 2. After the other spring member 7 is brought into contact with the shell 2, the shell 2 and the shell 5 are electrically connected to each other. As a result, improvement of EMI characteristics is expected.
Referring to FIG. 2 (a characteristic part of a connector disclosed as an invention in Patent Document 1), a cable connector 1 has a shell 2 provided with a friction lock groove 8 instead of the friction lock hole. The friction lock groove 8 is a recessed portion formed by utilizing a cut formed in the shell 2. The friction lock groove 8 has a bottom member 9 depressed inwards from a shell surface. When the cable connector 1 is connected to a board connector 4, a spring member 6 of the board connector 4 is fitted to the friction lock groove 8 to lock a connected state. Simultaneously, the spring member 6 is brought into contact with the bottom member 9. Therefore, improvement of EMI characteristics is expected.
The locking mechanism in which the spring member 6 is fitted to the locking hole 3 or the friction lock groove 8 as described above is called a friction locking mechanism.